chore: a few grammar updates (#121)

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lib/kafee/producer.ex

@@ -169,7 +169,7 @@ defmodule Kafee.Producer do
   were sent in your code. See `Kafee.Producer.TestAdapter` and
   `Kafee.Testing` for more information.
 
-  > #### OPT 26+ {: .info}
+  > #### OTP 26+ {: .info}
   >
   > If you are using OTP 26 or later, maps are no longer sorted in a consistent
   > way. This means if you are testing JSON formatted messages, there is a good

lib/kafee/test.ex

@@ -4,7 +4,7 @@ defmodule Kafee.Test do
 
   ## Note on sending from other processes
 
-  If you are sending emails from another process (for example,
+  If you are sending messages from another process (for example,
   from inside a `Task` or `GenServer`) you may need to use
   the shared mode. See the docs on `__using__/1` for more
   information.
@@ -53,8 +53,8 @@ defmodule Kafee.Test do
   Sometimes messages don't show up when asserting because you can send messages
   from a _different_ process than the test process. When that happens,
   turn on the shared mode. This will tell `Kafee.Producer.TestAdapter` to always
-  send the to the test process. This means that you cannot use shared mode with
-  async tests.
+  send the messages to the test process. This means that you cannot use shared
+  mode with async tests.
 
   Try to use this first:
 
@@ -139,7 +139,7 @@ defmodule Kafee.Test do
   end
 
   @doc """
-  Returns a list of messages that has been produced during
+  Returns a list of messages that have been produced during
   the test. We do _not_ recommend using this function as it
   can change between tests very easily.